1. Field of the Invention
The present invention relates to a method of treating certain synthetic textile materials such as filaments, fibers, yarns, and threads, more especially in pile form, so as to cause the longitudinal contraction of these materials, and of the resulting products.
2. Description of the Prior Art
Embossing of pile fabrics is conventionally accomplished by utilizing a hot embossing roll or plate having engraved thereon various designs or patterns. The hot embossing roll, in contact with a pile fabric, causes a certain shrinking of the fabric, thereby creating the desired decorative embossed effect.
Various techniques have been conceived so as to eliminate the disadvantageously expensive embossing roll. One of the most successful techniques for such has been that generally described as a chemical embossing method. Recently chemical embossing techniques for nylon pile fabric have been disclosed in a number of United States patents. In U.S. Pat. No. 3,849,157, such chemical embossing technique is described to occur by the application of an embossing composition comprising a liquid base vehicle blended with a metal halide and an acid. U.S. Pat. No. 3,849,158 discloses that various azoles can be substituted for such metal halide to achieve equivalent chemical embossing. Other related disclosures can be found in U.S. Pat. Nos. 3,849,159 and 3,953,164.
While the processes of the prior art result in sufficient embossing of nylon fabric so as to achieve the desired results, in order to achieve a satisfactory depth of embossing, high concentrations of the embossing composition must be used. These high concentrations require various protective devices to provide adequate safety for those working in these operations. Further, in order to avoid environmental damage, the reagents used in the embossing treatment should be recovered, such recovery adding significantly to the cost of the actual process. Attempts to obviate these problems by the use of low concentration, less harmful or disposable chemical systems do not result in satisfactory embossing.
Further, as a result of the high concentrations of reagents necessary to give the desired effects in commercially acceptable production times, residual salts and, in some cases, polymeric residues appear on the surface of the treated fabrics, detracting from the overall aesthetics of the final pile materials.